content: // Protocol Buffers - Google's data interchange format
  // Copyright 2008 Google Inc.  All rights reserved.
  // https://developers.google.com/protocol-buffers/
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions are
  // met:
  //
  //     * Redistributions of source code must retain the above copyright
  // notice, this list of conditions and the following disclaimer.
  //     * Redistributions in binary form must reproduce the above
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  package com.google.protobuf;
  
  import java.util.List;
  import java.util.Map;
  
  /**
   * Base interface for methods common to {@link Message} and
   * {@link Message.Builder} to provide type equivalency.
   *
   * @author jonp@google.com (Jon Perlow)
   */
  public interface MessageOrBuilder extends MessageLiteOrBuilder {
  
    // (From MessageLite, re-declared here only for return type covariance.)
    @Override
    Message getDefaultInstanceForType();
  
    /**
     * Returns a list of field paths (e.g. "foo.bar.baz") of required fields
     * which are not set in this message.  You should call
     * {@link MessageLiteOrBuilder#isInitialized()} first to check if there
     * are any missing fields, as that method is likely to be much faster
     * than this one even when the message is fully-initialized.
     */
    List<String> findInitializationErrors();
  
    /**
     * Returns a comma-delimited list of required fields which are not set
     * in this message object.  You should call
     * {@link MessageLiteOrBuilder#isInitialized()} first to check if there
     * are any missing fields, as that method is likely to be much faster
     * than this one even when the message is fully-initialized.
     */
    String getInitializationErrorString();
  
    /**
     * Get the message's type's descriptor.  This differs from the
     * {@code getDescriptor()} method of generated message classes in that
     * this method is an abstract method of the {@code Message} interface
     * whereas {@code getDescriptor()} is a static method of a specific class.
     * They return the same thing.
     */
    Descriptors.Descriptor getDescriptorForType();
  
    /**
     * Returns a collection of all the fields in this message which are set
     * and their corresponding values.  A singular ("required" or "optional")
     * field is set iff hasField() returns true for that field.  A "repeated"
     * field is set iff getRepeatedFieldCount() is greater than zero.  The
     * values are exactly what would be returned by calling
     * {@link #getField(Descriptors.FieldDescriptor)} for each field.  The map
     * is guaranteed to be a sorted map, so iterating over it will return fields
     * in order by field number.
     * <br>
     * If this is for a builder, the returned map may or may not reflect future
     * changes to the builder.  Either way, the returned map is itself
     * unmodifiable.
     */
    Map<Descriptors.FieldDescriptor, Object> getAllFields();
  
    /**
     * Returns true if the given oneof is set.
     * @throws IllegalArgumentException if
     *           {@code oneof.getContainingType() != getDescriptorForType()}.
     */
    boolean hasOneof(Descriptors.OneofDescriptor oneof);
  
    /**
     * Obtains the FieldDescriptor if the given oneof is set. Returns null
     * if no field is set.
     */
    Descriptors.FieldDescriptor getOneofFieldDescriptor(
        Descriptors.OneofDescriptor oneof);
  
    /**
     * Returns true if the given field is set.  This is exactly equivalent to
     * calling the generated "has" accessor method corresponding to the field.
     * @throws IllegalArgumentException The field is a repeated field, or
     *           {@code field.getContainingType() != getDescriptorForType()}.
     */
    boolean hasField(Descriptors.FieldDescriptor field);
  
    /**
     * Obtains the value of the given field, or the default value if it is
     * not set.  For primitive fields, the boxed primitive value is returned.
     * For enum fields, the EnumValueDescriptor for the value is returned. For
     * embedded message fields, the sub-message is returned.  For repeated
     * fields, a java.util.List is returned.
     */
    Object getField(Descriptors.FieldDescriptor field);
  
    /**
     * Gets the number of elements of a repeated field.  This is exactly
     * equivalent to calling the generated "Count" accessor method corresponding
     * to the field.
     * @throws IllegalArgumentException The field is not a repeated field, or
     *           {@code field.getContainingType() != getDescriptorForType()}.
     */
    int getRepeatedFieldCount(Descriptors.FieldDescriptor field);
  
    /**
     * Gets an element of a repeated field.  For primitive fields, the boxed
     * primitive value is returned.  For enum fields, the EnumValueDescriptor
     * for the value is returned. For embedded message fields, the sub-message
     * is returned.
     * @throws IllegalArgumentException The field is not a repeated field, or
     *           {@code field.getContainingType() != getDescriptorForType()}.
     */
    Object getRepeatedField(Descriptors.FieldDescriptor field, int index);
  
    /** Get the {@link UnknownFieldSet} for this message. */
    UnknownFieldSet getUnknownFields();
  }
  